Fluid pumps and motors

ABSTRACT

A fluid pump or motor of the rotary sliding vane type comprising a housing having a bore within which is disposed a unitary peripheral cam ring sandwiched between a pair of cheek plates. A sliding vane type rotor is rotatably mounted within the cam ring on a shaft extending axially through the housing bore, the cam ring being shaped to form a pair of diametrically opposed working zones between the cam ring internal surface and the periphery of the rotor. The ends of the working zones are respectively connected to fluid inlet and outlet ports through bores radially extending through the cam ring. The cam ring is axially split preferably at the location of a radially extending bore communicating low pressure fluid to the working zones such that high pressure fluid therein will radially expand the cam ring into a sealing engagement with the housing bore to prevent fluid leakage around the periphery of the cam ring. A method of manufacturing the split cam ring is also disclosed.

United States Patent [191 Rosaen Jan. 29, 1974 FLUID PUMPS AND MOTORS [76] Inventor: Oscar E. Rosaen, 5l Roslyn Rd.,

Grosse Pointe, Mich. 48236 [22] Filed: Jam-6, 1972 [21] Appl. No.: 215,761

[52] US. Cl 418/108, 418/156, 418/157 [51] Int. Cl. F0lc 19/00 [58] Field of Search... 418/107, 108, 156, 149, 270,

[56] I References Cited UNITED STATES PATENTS 2,385,069 9/1945 Ferris; 418/24 X 2,238,786 4/1941 Warman 418/24 X 3,547,562 12/1970 Cynor 418/31 Primary Examiner-Carlton R. Croyle Assistant Examiner-Michael Koczo, Jr. Attorney, Agent, or Firm-Robert C. Hauke et a1.

[ 5 7 ABSTRACT A fluid pump or motor of the rotary sliding vane type comprising a housing having a bore within which is disposed a unitary peripheral cam ring sandwiched between a pair of cheek plates. A sliding vane type rotor is rotatably mounted within the cam ring on a shaft extending axially through the housing bore, the cam ring being shaped to form a pair of diametrically opposed working zones between the cam ring internal surface and the periphery of the rotor. The ends of the working zones are respectively connected to fluid inlet and outlet ports through bores radially extending through the cam ring. The cam ring is axially split preferably at the location of a radially extending bore communicating low pressure fluid to the working zones such that high pressure fluid therein will radially expand the cam ring into a sealing engagement with the housing bore to prevent fluid leakage around the periphery of the cam ring. A method of manufacturing the split cam ring is also disclosed.

13 Claims, 4 Drawing Figures FLUID PUMPS AND MOTORS BACKGROUND OF THE INVENTION unitary peripheral cam ring is so contoured as to form a cam track within which is rotatably mounted a rotor carrying radially sliding vanes, the outer ends of which engage the cam track. The periphery of the rotor, the

cam track andthe opposing sides of the cheek plate 7 form fluid working zones. Suitable inlet and outlet porting arrangements, such as a pair of diametrically opposed bores radially extending through the cam ring, respectively connect the ends of the working zones to a source of fluid and to a user of the pressure fluid delivered by the device when the device is operative as a pump, and to a source of pressure fluid and a reservoir when the device is operative as a motor.

Although such devices heretofore may have functioned in an acceptable manner, a common problem is that the diameter of the housing bore and the outer diameter of a unitary peripheral cam ring must be made with extremely close tolerance, otherwise high pressure fluid will leak around the outer peripheral surface of the cam ring with a resultant drop in the volumetric efficiency of the device. In an attempt to overcome this problem, devices have been made with the cam track formed on the inner diameter of the housing bore, the inlet and outlet porting'being disposed adjacent the rotor and communicating through passageways in the housing. However, this method of construction is very expensive and is thus employed in only very high performance vane pumps and motors.

Another technique used in attempting to solve the problem is to press-fit the outer surface of the cam ring into the housing bore which, in addition to requiring close tolerances with resultant high cost, may result in an undesirable deformation of the cam track formed on the inner surface of the cam ring, with a resultant noisy pump or motor operation.

It is therefore desirable to provide a fluid pump or fluid motor which is of a simple construction, efficient in operation, and which does not have the disadvantages of the devices heretofore described.

SUMMARY OF THE INVENTION The present invention, which will be subsequently described in greater detail, is involved with a fluid pump or motor having a housing with inlet and outlet ports communicating with an axial bore within which is disposed a unitary peripheral cam ring sandwiched between a pair of axially aligned cheek plates. A working rotor is rotatably mounted within the cam ring, which is formed to provide fluid working zones between the outer periphery of the rotor and the inner periphery of the cam ring. The ends of the fluid working zones respectively communicate with the inlet and outlet ports through bores radially extending through the cam ring. The essence of the of the invention resides in the unitary cam ring being axially split preferably at the location of a bore that communicates with the low pressure end of a working zone. In operation, high pressure in the working zones will radially expand the cam ring into sealing engagement with the housing bore, preventing leakage around the periphery of the cam ring. Thus, the cam ring and bore need not be manufactured to such close tolerance as heretofore has been necessary and volumetric efficiency is maintained, resulting in an improved, more efficient and longer wearing fluid pressure pump or motor. The separation, or split, is such that on expansion the gap provided is of extremely small dimension and will not cause vane wear or noise.

A preferred method of manufacturing the cam ring comprises forming a ring having a cylindrical outer surface and a cam track on the inner surface. The cam ring is then cracked across one portion thereof such that the ring which remains a unitary component, is angularly separable at the crack.

Other objects, advantages, and application of the present invention will become apparent to those skilled in the art of fluid pumps and fluid motors when the accompanying description of an example of the best mode contemplated to practice the invention is read in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The description herein makes reference to the accompanying drawings wherein like reference characters refer to like parts throughout the several views, and in which:

FIG. 1 isa longitudinal cross-sectional view of a fluid device constructed in accordance with the principles of the present invention and taken on the line 11 of FIG. 3;

FIG. 2 is a longitudinal cross-sectional view of the fluid device taken on the line 22 of FIG. 3;

FIG. 3 is a transverse cross-sectional view of the fluid device taken on the line 3-3 of FIG. 1; and,

FIG. 4 is an enlarged fragmentary perspective view of a portion of the cam ring of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawings illustrate a fluid pumpl0 of the rotary sliding vane type, however, it is to be understood that the invention disclosed herein is equally applicable for use in fluid motors.

A housing 12 of the fluid pump 10 comprises a body section 14 and an end cover 16 which is secured to the body section 14 by screws 18. The body section 14 has an enlarged axial bore 20, the end wall 22 of which has an opening 24 through which extends a drive shaft 26. A pumping stack, generally indicated at 28 and disposed within the axial bore 20, comprises, as viewed from right to left in FIG. 1, a wear plate 30, a unitary peripheral cam ring 32, a rotor 34, a second wear plate 36 and a cheek plate 38. Although the end wall 22 is integral with the housing 12, the end wall 22 funcsmsas qs ndqhsel p atq- The c ring 32 and forms no part of the invention, it will not be described any more fully herein.

The shaft 26 is rotatably mounted within bearings 42 and 44 respectively located within the cheek plate 38 and the opening 24 of the housing 12. A dowel pin 46, shown in FIG. 3, extends through the pumping stack 28 to maintain a proper angular alignment between the components thereof. Suitable sealing means 48 around the shaft 26 at the opening 24 prevents leakage from the housing 12.

Referring to FIG. 3, the contour of the inner surface of the cam ring 32 forms a cam track 58 substan ti ally elliptical in shape, which together with the outer periphery of the rotor 34 mounted therein and the adjacent surfaces of the wear plates 30 and 36 define two opposed working zones or chambers indicated by the numerals 60 and 62, each of which has a fluid inlet and a fluid outlet end, to form a sliding vane pump of the double-throw type having diametrically opposed fluid inlet zones and diametrically opposed fluid outlet zones. The ends of the working chambers 60 and 62 respectively register with diametrically opposed fluid inlet port openings 64 and 66 radially extending through the cam ring 32, and diametrically opposed fluid delivery port openings 68 and 70 angularly spaced from the openings 64 and 66 and radially extending through the cam ring 32.

The cam track 58 of the cam ring 32 includes an inlet zone ramp extending from A to B, a dwell portion extending from B to C, a delivery zone ramp extending from C to D and another dwell portion extending from D to E. Since the cam track 58 is symmetrical about each of its major and minor axes, each of the ramps and dwell portions from A to E is duplicated in the remaining opposite portion of the cam track 58.

The rotor 34 has a plurality of radially extending vanes 72 slidably mounted therein, the outer ends of the vanes 72 being adapted to engage the cam track 58, being urged outwardly against the cam track 58 to displace fluid from the inlet zones to the outlet zones as the rotor 34 rotates within the cam ring 32.

As can best be seen in FIGS. 2 and 3, fluid is supplied to the inlet port openings 64 and 66 through the cam ring 32 by passageways 74 and 78 connected by an annular groove 80 and openly communicating with a radially extending fluid inlet connection'port 76 adapted to be connected to a reservoir or the like.

As can best be seen in FIGS. 1 and 3, the outlet delivery port openings 68 and 70 through the cam ring 32 communicate with a fluid outlet connection port 82 by means of delivery passageways 84 and 88 and an annular passageway 86 within the housing 12 surrounding and radially spaced from the drive shaft 26. Fluid discharged from the outlet zones within the cam ring 32 is discharged through the outlet connection port 82 for delivery to a fluid user, such as a fluid motor or the like.

During operation of the pump 10, fluid enters from th inlet connection port 76 and flows through the passageway 74 to the cam ring inlet port opening 64, while at the same time fluid flows around the cheek plate 38 via the annular groove 80 to the second passageway 78 and to the cam ring inlet port opening 66 thereby simultaneously providing fluid to the fluid inlet zones on both sides of the cam ring 32, whereupon the vanes 72 rotating within the cam track 58 pressurize and pump fluid through the opposing cam ring delivery port openings 68 and 70 to the delivery passageways 84'and 88 where the fluid is discharged from the pump 10 through the outlet connection port 82.

As hereinbefore indicated, a major problem of pumps of the type herein described is the leakage of pressure fluid from the pressure outlet via the clearance space formed between the housing bore and the outer periphery of the cam ring. This leakage is eliminated in the present invention by providing the cam ring 32 with a slotted portion 112 (FIGS. 3 and 4) extending radially through and axially across one side of the cam ring 32. The slotted portion 112 is shown as being located transversely of the cam ring inlet port opening 64, but it may alternately be formed at a location associated with the other cam ring inlet port opening 66, or even across some other section of the cam ring adjacent any low pressure zone. The section of the cam ring 32 below the blind end 113 of the slotted portion 112 has been cracked, as indicated by the numeral 114, by any suitable means which will not remove cam ring material, such that the cam ring 32- is angularly separable at the crack 114 when high pressure fluid in the delivery zone exerts a radially directed force on the inner surface of the cam ring 32, causing the cam ring 32 to expand radially outwardly a slight but sufficient distance to cause its peripheral outer surface to sealingly engage the internal peripheral surface of the a a h elor thsre ymro di s an x eme y i ple and inexpensive means to overcome the aforementioned leakage problem. It can be seen that by providing the slotted portion 112 in the cam ring 32, the crack 114 extending across the full bottom of the slotted portion 1 12 to the inner surface of the cam ring 32 may be simply achieved without the necessity of removing any material from the inner surface of the cam ring 32 and thereby minimizing wear on the outer tip of the vanes 72 as they traverse the cam track 58 as would be the case if the slotted portion 112 extended completely through the cam ring 32. Since the expansion of the cam ring 32 is very slight, the effect of the crack 114 on the outer tips of the vanes 72 is minimal and will not cause any perceptible noise or appreciable wear. The cam ring 32 is preferably made of a high quality steel in which the necessary cam track 58 is formed thereon by conventional machine processes, as is the slotted portion 112. The cam ring 32 is then preferably heat treated in the conventional manner for hardening, thereafter being split to form the crack 114 by any means, such as striking it with a hammer or other tool.

It can thus be seen that the present invention has provided a new and improvedfluid pump or motor of the rotary vane type in which leakage around the periphery of a cam ring is eliminated by a simple and inexpensive method of constructing the cam ring.

Although only one form of the present invention has been disclosed, it will be understood by those skilled in the art of fluid pumps and motors that other changes and modifications may be made which come within the spirit of the invention and the scope of the appended claims. I

What is claimed is as follows:

1. A fluid pump or motor device comprising:

low and high pressure fluid conducting means, one of which is an inlet means and the other an outlet means;

a housing having a bore therein;

a unitary cam ring in said housing bore;

a working rotor rotatably disposed within said cam ring;

said cam ring being formed to provide at least one working zone between the inner peripheral suface of said cam ring and the outer peripheral surface of said rotor, said working zone having end portions respectively in fluid communication with said inlet and said outlet means;

said unitary cam ring having a separable portion and being radially expandable when the inner surface thereof is subjected to pressure whereby the outer surface of said cam ring sealingly engages said housing bore to prevent fluid leakage around the periphery of said cam ring.

2. The device as defined in claim I wherein said cam ring has a circular outer periphery and an inner surface of a predetermined contour forming a cam track, said cam ring being split between said inner and outer surfaces at a location associated with that end of said working zone which is subjected to the lesser pressure.

3. The device as defined in claim 1 wherein said cam ring has a radially extending opening communicating one end of said working zone with said inlet means and a second radially extending opening communicating the other end of said working zone with said outlet means, said cam ring having a split portion forming said separable portion, said split portion being associated with the end of said working zone in communication with the low pressure fluid conducting means.

4. The device as defined in claim 1 comprising a second working zone, and wherein said cam ring has a pair of diametrically opposed openings radially extending from its inner surface to its outer surface and communicating said end portion of each working zone with said inlet means; and said cam ring having a second pair of diametrically opposed openings angularly spaced from said first mentioned pair of openings and radially extending from its inner surface to its outer surface for communicating said other end portions of said working zones with said outlet means; said cam ring being split at a location associated with one of the pair of openings in communication with the low pressure fluid conducting means.

5. The device as defined in claim 3 wherein said split portion is disposed across said cam ring opening.

6. The device as defined in claim 3 wherein said split portion at least in part comprises a crack extending across the inner surface of said cam ring.

7. As a new article of manufacture for use within a fluid pressure energy translating device of the type having low and high pressure fluid conducting means in a housing having a bore therein with a working rotor rotatably mounted within the housing, said new article of manufacture comprising:

a unitary cam ring having parallel opposing sides connccting inner and outer peripheral surfaces, the outer surface of said cam ring being contoured to engage the housing bore in a fluid sealing relationship, the inner surface of said cam ring being contoured in such a manner as to cooperate with the working rotor to form at least one working zone, said cam ring having an opening extending from the inner surface to the outer surface thereof to provide fluid communication between one end of said zone and the low pressure fluid means, said cam ring being split from the inner to the outer surface thereof at a location associated with said end of said working zone whereby high pressure fluid in said working zone acts against the inner surface of said cam ring to expand same radially outward into a sealing engagement with said housing bore.

8. The new article of manufacture as defined in claim 7 further comprising a second working zone, and wherein said cam ring has a first pair of diametrically opposed openings extending from its inner surface to its outer surface for communicating one end of each of said working zones with the low pressure conducting means, and a second pair of diametrically opposed openings angularly spaced from said first mentioned pair of openings, said second openings extending from the inner surface to the outer surface of said camri'ng for providing fluid communication from the other ends of said zones to said high pressure fluid conducting means; said cam .ring being split at a location associated with one of said first mentioned pair of diametrically opposed bores.

9. The article as defined in claim 7 wherein said cam ring is split across said opening.

10. The article as defined in claim 7 wherein said cam ring has a crack extending across the inner surface of said cam ring.

11. A rotary vane fluid pump or motor device comprising:

a housing having low and high pressure fluid conducting means;

a bore in said housing;

a unitary peripheral cam ring within said housing bore, said cam ring having an inner peripheral surface forming a cam track;

a rotor rotatably disposed within said cam ring, said rotor having a plurality of radially sliding vanes, the

'outer ends of which engage said cam track, said cam ring formed to provide a fluid inlet zone and fluid outlet zones between said cam track and the outer periphery of said rotor as said rotor rotates;

said cam ring having a first pair of diametrically opposed openings extending radially from its inner surface to its outer surface for communicating fluid from one of said fluid zones to said low pressure fluid conducting means, and a second pair of diametrically opposed openings angularly spaced from said first mentioned openings, said second openings extending radially from the inner surface to the outer surface of said cam ring for communicating fluid from the other of said zones to said high pressure fluid conducting means;

said cam ring being split at a location associated with one of saidfirst mentioned openings such that pressure acting on the inner surface'of said cam ring radially expands said cam ring into a sealing engagement with said housing bore.

12. A method of manufacturing a cam ring adapted for use in a pump or motor device, comprising:

forming a ring having a cylindrical outer surface and an inner surface cam track, said cam track having two diametrically opposed inlet ramps and two diametrically opposed outlet ramps, said cam track having minor transition zones between one terminus of each outlet and inlet ramp and having a major transition zone between the other terminus of each inlet and outlet ramp;

forming a slot extending axially through the cam ring from the one side to the other and radially downfor use in a pump or motor device, comprising:

forming a ring having a cylindrical outer surface and a cam track inner surface; and cracking said ring across one portion thereof so that the cam ring is angularly separable at said crack under radial outward pressure to enlarge the diameter of said ring outer surface. 11

. UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,788,783 Dated Jan. 29, 1974 Inventor(s) Oscar E. Rosaen It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

8 Column 1, line 11, after "mounted a" insert --unitary peripheral-q Column 1, line 13, after "the" delete "unitary peripheral";

Column 1, line 17, delete "plate" and insert plates--;

Column 3, line 58,-delete "th" and insert -the;

, Column 5, line 31, after "1" insert -further-.

Signed and sealed this 11th day of June 197 (SEAL) Attest:

EUJARD M.F'LETCHER,JR.I V C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O (10-69) uscoMM-Dc 60376-P69 U,S. GOVINMENT PRINTING OFFICE I919 0-366-33 

1. A fluid pump or motor device comprising: low and high pressure fluid conducting means, one of which is an inlet means and the other an outlet means; a housing having a bore therein; a unitary cam ring in said housing bore; a working rotor rotatably disposed within said cam ring; said cam ring being formed to provide at least one working zone between the inner peripheral suface of said cam ring and the outer peripheral surface of said rotor, said working zone having end portions respectively in fluid communication with said inlet and said outlet means; said unitary cam ring having a separable portion and being radially expandable when the inner surface thereof is subjected to pressure whereby the outer surface of said cam ring sealingly engages said housing bore to prevent fluid leakage around the periphery of said cam ring.
 2. The device as defined in claim 1 wherein said cam ring has a circular outer periphery and an inner surface of a predetermined contour forming a cam track, said cam ring being split between said inner and outer surfaces at a location associated with that end of said working zone which is subjected to the lesser pressure.
 3. The device as defined in claim 1 wherein said cam ring has a radially extending opening communicating one end of said working zone with said inlet mEans and a second radially extending opening communicating the other end of said working zone with said outlet means, said cam ring having a split portion forming said separable portion, said split portion being associated with the end of said working zone in communication with the low pressure fluid conducting means.
 4. The device as defined in claim 1 comprising a second working zone, and wherein said cam ring has a pair of diametrically opposed openings radially extending from its inner surface to its outer surface and communicating said end portion of each working zone with said inlet means; and said cam ring having a second pair of diametrically opposed openings angularly spaced from said first mentioned pair of openings and radially extending from its inner surface to its outer surface for communicating said other end portions of said working zones with said outlet means; said cam ring being split at a location associated with one of the pair of openings in communication with the low pressure fluid conducting means.
 5. The device as defined in claim 3 wherein said split portion is disposed across said cam ring opening.
 6. The device as defined in claim 3 wherein said split portion at least in part comprises a crack extending across the inner surface of said cam ring.
 7. As a new article of manufacture for use within a fluid pressure energy translating device of the type having low and high pressure fluid conducting means in a housing having a bore therein with a working rotor rotatably mounted within the housing, said new article of manufacture comprising: a unitary cam ring having parallel opposing sides connecting inner and outer peripheral surfaces, the outer surface of said cam ring being contoured to engage the housing bore in a fluid sealing relationship, the inner surface of said cam ring being contoured in such a manner as to cooperate with the working rotor to form at least one working zone, said cam ring having an opening extending from the inner surface to the outer surface thereof to provide fluid communication between one end of said zone and the low pressure fluid means, said cam ring being split from the inner to the outer surface thereof at a location associated with said end of said working zone whereby high pressure fluid in said working zone acts against the inner surface of said cam ring to expand same radially outward into a sealing engagement with said housing bore.
 8. The new article of manufacture as defined in claim 7 further comprising a second working zone, and wherein said cam ring has a first pair of diametrically opposed openings extending from its inner surface to its outer surface for communicating one end of each of said working zones with the low pressure conducting means, and a second pair of diametrically opposed openings angularly spaced from said first mentioned pair of openings, said second openings extending from the inner surface to the outer surface of said cam ring for providing fluid communication from the other ends of said zones to said high pressure fluid conducting means; said cam ring being split at a location associated with one of said first mentioned pair of diametrically opposed bores.
 9. The article as defined in claim 7 wherein said cam ring is split across said opening.
 10. The article as defined in claim 7 wherein said cam ring has a crack extending across the inner surface of said cam ring.
 11. A rotary vane fluid pump or motor device comprising: a housing having low and high pressure fluid conducting means; a bore in said housing; a unitary peripheral cam ring within said housing bore, said cam ring having an inner peripheral surface forming a cam track; a rotor rotatably disposed within said cam ring, said rotor having a plurality of radially sliding vanes, the outer ends of which engage said cam track, said cam ring formed to provide a fluid inlet zone and fluid outlet zones between said cam track and the outer periphery of said rotor as said rotor rotates; said cam ring having a first pair of diametrically opposed openings extending radially from its inner surface to its outer surface for communicating fluid from one of said fluid zones to said low pressure fluid conducting means, and a second pair of diametrically opposed openings angularly spaced from said first mentioned openings, said second openings extending radially from the inner surface to the outer surface of said cam ring for communicating fluid from the other of said zones to said high pressure fluid conducting means; said cam ring being split at a location associated with one of said first mentioned openings such that pressure acting on the inner surface of said cam ring radially expands said cam ring into a sealing engagement with said housing bore.
 12. A method of manufacturing a cam ring adapted for use in a pump or motor device, comprising: forming a ring having a cylindrical outer surface and an inner surface cam track, said cam track having two diametrically opposed inlet ramps and two diametrically opposed outlet ramps, said cam track having minor transition zones between one terminus of each outlet and inlet ramp and having a major transition zone between the other terminus of each inlet and outlet ramp; forming a slot extending axially through the cam ring from the one side to the other and radially downward from the outer surface to a predetermined distance from the cam ring inner surface; and cracking said cam ring axially between the opposite side surfaces of said cam ring and radially between the blind portion of said slot and said inner surface such that said cam ring is angularly separable at said crack.
 13. A method of manufacturing a cam ring adapted for use in a pump or motor device, comprising: forming a ring having a cylindrical outer surface and a cam track inner surface; and cracking said ring across one portion thereof so that the cam ring is angularly separable at said crack under radial outward pressure to enlarge the diameter of said ring outer surface. 